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bulletproofs: merge multiexps as per sarang's new python code

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pull/127/head
moneromooo-monero 6 years ago
parent 4061960a16
commit fc9f7d9c81
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GPG Key ID: 686F07454D6CEFC3
1 changed files with 38 additions and 68 deletions
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106
src/ringct/bulletproofs.cc
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@ -91,28 +91,6 @@ static inline bool is_reduced(const rct::key &scalar)
return sc_check(scalar.bytes) == 0;
}
static void add_acc_p3(ge_p3 *acc_p3, const rct::key &point)
{
ge_p3 p3;
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&p3, point.bytes) == 0, "ge_frombytes_vartime failed");
ge_cached cached;
ge_p3_to_cached(&cached, &p3);
ge_p1p1 p1;
ge_add(&p1, acc_p3, &cached);
ge_p1p1_to_p3(acc_p3, &p1);
}
static void sub_acc_p3(ge_p3 *acc_p3, const rct::key &point)
{
ge_p3 p3;
CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&p3, point.bytes) == 0, "ge_frombytes_vartime failed");
ge_cached cached;
ge_p3_to_cached(&cached, &p3);
ge_p1p1 p1;
ge_sub(&p1, acc_p3, &cached);
ge_p1p1_to_p3(acc_p3, &p1);
}
static rct::key get_exponent(const rct::key &base, size_t idx)
{
static const std::string salt("bulletproof");
@ -733,6 +711,7 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
// sanity and figure out which proof is longest
size_t max_length = 0;
size_t nV = 0;
for (const Bulletproof *p: proofs)
{
const Bulletproof &proof = *p;
@ -749,6 +728,7 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
CHECK_AND_ASSERT_MES(proof.L.size() > 0, false, "Empty proof");
max_length = std::max(max_length, proof.L.size());
nV += proof.V.size();
}
CHECK_AND_ASSERT_MES(max_length < 32, false, "At least one proof is too large");
size_t maxMN = 1u << max_length;
@ -757,13 +737,13 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
const size_t N = 1 << logN;
rct::key tmp;
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(nV + (2 * (10/*logM*/ + logN) + 4) * proofs.size() + 2 * maxMN);
// setup weighted aggregates
rct::key Z0 = rct::identity();
rct::key z1 = rct::zero();
rct::key &Z2 = Z0;
rct::key z3 = rct::zero();
rct::keyV z4(maxMN, rct::zero()), z5(maxMN, rct::zero());
rct::key Y2 = rct::identity(), &Y3 = Y2, &Y4 = Y2;
rct::key y0 = rct::zero(), y1 = rct::zero();
for (const Bulletproof *p: proofs)
{
@ -773,7 +753,8 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
for (logM = 0; (M = 1<<logM) <= maxM && M < proof.V.size(); ++logM);
CHECK_AND_ASSERT_MES(proof.L.size() == 6+logM, false, "Proof is not the expected size");
const size_t MN = M*N;
rct::key weight = rct::skGen();
const rct::key weight_y = rct::skGen();
const rct::key weight_z = rct::skGen();
// Reconstruct the challenges
PERF_TIMER_START_BP(VERIFY_start);
@ -795,10 +776,11 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
rct::key proof8_T1 = rct::scalarmult8(proof.T1);
rct::key proof8_T2 = rct::scalarmult8(proof.T2);
rct::key proof8_S = rct::scalarmult8(proof.S);
rct::key proof8_A = rct::scalarmult8(proof.A);
PERF_TIMER_START_BP(VERIFY_line_61);
// PAPER LINE 61
sc_muladd(y0.bytes, proof.taux.bytes, weight.bytes, y0.bytes);
sc_muladd(y0.bytes, proof.taux.bytes, weight_y.bytes, y0.bytes);
const rct::keyV zpow = vector_powers(z, M+3);
@ -814,26 +796,26 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
PERF_TIMER_START_BP(VERIFY_line_61rl_new);
sc_muladd(tmp.bytes, z.bytes, ip1y.bytes, k.bytes);
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(proof.V.size());
sc_sub(tmp.bytes, proof.t.bytes, tmp.bytes);
sc_muladd(y1.bytes, tmp.bytes, weight.bytes, y1.bytes);
sc_muladd(y1.bytes, tmp.bytes, weight_y.bytes, y1.bytes);
for (size_t j = 0; j < proof8_V.size(); j++)
{
multiexp_data.emplace_back(zpow[j+2], proof8_V[j]);
sc_mul(tmp.bytes, zpow[j+2].bytes, weight_y.bytes);
multiexp_data.emplace_back(tmp, proof8_V[j]);
}
rct::addKeys(Y2, Y2, rct::scalarmultKey(multiexp(multiexp_data, false), weight));
sc_mul(tmp.bytes, x.bytes, weight.bytes);
rct::addKeys(Y3, Y3, rct::scalarmultKey(proof8_T1, tmp));
sc_mul(tmp.bytes, x.bytes, weight_y.bytes);
multiexp_data.emplace_back(tmp, proof8_T1);
rct::key xsq;
sc_mul(xsq.bytes, x.bytes, x.bytes);
sc_mul(tmp.bytes, xsq.bytes, weight.bytes);
rct::addKeys(Y4, Y4, rct::scalarmultKey(proof8_T2, tmp));
sc_mul(tmp.bytes, xsq.bytes, weight_y.bytes);
multiexp_data.emplace_back(tmp, proof8_T2);
PERF_TIMER_STOP(VERIFY_line_61rl_new);
PERF_TIMER_START_BP(VERIFY_line_62);
// PAPER LINE 62
rct::addKeys(Z0, Z0, rct::scalarmultKey(rct::addKeys(rct::scalarmult8(proof.A), rct::scalarmultKey(proof8_S, x)), weight));
multiexp_data.emplace_back(weight_z, proof8_A);
sc_mul(tmp.bytes, x.bytes, weight_z.bytes);
multiexp_data.emplace_back(tmp, proof8_S);
PERF_TIMER_STOP(VERIFY_line_62);
// Compute the number of rounds for the inner product
@ -909,8 +891,8 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
sc_mulsub(h_scalar.bytes, tmp.bytes, yinvpow.bytes, h_scalar.bytes);
}
sc_muladd(z4[i].bytes, g_scalar.bytes, weight.bytes, z4[i].bytes);
sc_muladd(z5[i].bytes, h_scalar.bytes, weight.bytes, z5[i].bytes);
sc_muladd(z4[i].bytes, g_scalar.bytes, weight_z.bytes, z4[i].bytes);
sc_muladd(z5[i].bytes, h_scalar.bytes, weight_z.bytes, z5[i].bytes);
if (i == 0)
{
@ -928,55 +910,43 @@ bool bulletproof_VERIFY(const std::vector<const Bulletproof*> &proofs)
// PAPER LINE 26
PERF_TIMER_START_BP(VERIFY_line_26_new);
multiexp_data.clear();
multiexp_data.reserve(2*rounds);
sc_muladd(z1.bytes, proof.mu.bytes, weight.bytes, z1.bytes);
sc_muladd(z1.bytes, proof.mu.bytes, weight_z.bytes, z1.bytes);
for (size_t i = 0; i < rounds; ++i)
{
sc_mul(tmp.bytes, w[i].bytes, w[i].bytes);
sc_mul(tmp.bytes, tmp.bytes, weight_z.bytes);
multiexp_data.emplace_back(tmp, proof8_L[i]);
sc_mul(tmp.bytes, winv[i].bytes, winv[i].bytes);
sc_mul(tmp.bytes, tmp.bytes, weight_z.bytes);
multiexp_data.emplace_back(tmp, proof8_R[i]);
}
rct::key acc = multiexp(multiexp_data, false);
rct::addKeys(Z2, Z2, rct::scalarmultKey(acc, weight));
sc_mulsub(tmp.bytes, proof.a.bytes, proof.b.bytes, proof.t.bytes);
sc_mul(tmp.bytes, tmp.bytes, x_ip.bytes);
sc_muladd(z3.bytes, tmp.bytes, weight.bytes, z3.bytes);
sc_muladd(z3.bytes, tmp.bytes, weight_z.bytes, z3.bytes);
PERF_TIMER_STOP(VERIFY_line_26_new);
}
// now check all proofs at once
PERF_TIMER_START_BP(VERIFY_step2_check);
ge_p3 check1;
ge_double_scalarmult_base_vartime_p3(&check1, y1.bytes, &ge_p3_H, y0.bytes);
sub_acc_p3(&check1, Y2);
if (!ge_p3_is_point_at_infinity(&check1))
{
MERROR("Verification failure at step 1");
return false;
}
ge_p3 check2;
sc_sub(tmp.bytes, rct::zero().bytes, z1.bytes);
ge_double_scalarmult_base_vartime_p3(&check2, z3.bytes, &ge_p3_H, tmp.bytes);
add_acc_p3(&check2, Z0);
std::vector<MultiexpData> multiexp_data;
multiexp_data.reserve(2 * maxMN);
sc_sub(tmp.bytes, rct::zero().bytes, y0.bytes);
sc_sub(tmp.bytes, tmp.bytes, z1.bytes);
multiexp_data.emplace_back(tmp, rct::G);
sc_sub(tmp.bytes, z3.bytes, y1.bytes);
multiexp_data.emplace_back(tmp, rct::H);
for (size_t i = 0; i < maxMN; ++i)
{
multiexp_data.emplace_back(z4[i], Gi_p3[i]);
multiexp_data.emplace_back(z5[i], Hi_p3[i]);
sc_sub(tmp.bytes, rct::zero().bytes, z4[i].bytes);
multiexp_data.emplace_back(tmp, Gi_p3[i]);
sc_sub(tmp.bytes, rct::zero().bytes, z5[i].bytes);
multiexp_data.emplace_back(tmp, Hi_p3[i]);
}
sub_acc_p3(&check2, multiexp(multiexp_data, true));
PERF_TIMER_STOP(VERIFY_step2_check);
if (!ge_p3_is_point_at_infinity(&check2))
if (!(multiexp(multiexp_data, false) == rct::identity()))
{
MERROR("Verification failure at step 2");
PERF_TIMER_STOP(VERIFY_step2_check);
MERROR("Verification failure");
return false;
}
PERF_TIMER_STOP(VERIFY_step2_check);
PERF_TIMER_STOP(VERIFY);
return true;

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